This application claims priority to and the benefit of Korean Patent Application No. 2002-26449 filed on May 14, 2002 in the Korean Intellectual Property Office, the content of which is incorporated herein by reference.
(a) Field of the Invention
The present invention relates to a plasma display panel (PDP) driving device and method. More specifically, the present invention relates to a sustain and discharge circuit of a PDP.
(b) Description of the Related Art
In general, a PDP is a flat plate display for displaying characters or images using plasma generated by gas discharge. Pixels ranging from hundreds of thousands to more than millions are arranged in a matrix form according to the size of the PDP. PDPs are categorized as direct current (DC) PDPs and alternating current (AC) PDPs according to patterns of the waveforms of applied driving voltages and structures of discharge cells.
Current directly flows in discharge spaces while a voltage is supplied to the DC PDP, because electrodes of the DC PDP are exposed to the discharge spaces. Therefore, a resistor for restricting the current must be provided to the DC PDP. On the other hand, in the case of the AC PDP, the current is restricted due to the natural formation of a capacitance component because a dielectric layer covers the electrodes. The AC PDP has a longer life than the DC PDP, since the electrodes are protected against shock caused by ions during discharge.
In general, a method for driving the AC PDP includes a reset period, an addressing period, a sustain period, and an erase period.
In the reset period, the states of the respective cells are reset in order to smoothly address the cells. In the addressing period, the cells that are turned on and the cells that are not turned on in a panel are selected, and wall charges are accumulated to the cells that are turned on (i.e., the addressed cells). In the sustain period, discharge is performed in order to actually display pictures on the addressed cells. In the erase period, the wall charges of the cells are reduced to thereby terminate sustain-discharge.
In the AC PDP, since a sustain electrode and a scan electrode for sustain and discharge of the PDP operate as a capacitive load, a capacitor is provided between the scan electrode and the sustain electrode, and it will be equivalently referred to as a panel capacitor hereinafter. Therefore, reactive power is required in addition to the discharging power in order to apply waveforms for the sustain-discharge to the scan and sustain electrodes. A circuit for recovering and re-using the reactive power is referred to as a power recovery circuit. L. F. Weber discloses the power recovery circuits in U.S. Pat. Nos. 4,866,349 and 5,081,400, and Ooba also discloses them in Japanese Patent no. 2,755,201.
However, the sustain and discharge circuit proposed by the Weber patent requires an external capacitor used for a power recovery capacitor, the electric potential of which is to maintain half Vs. To achieve this, the capacity of the power recovery capacitor must be much greater than that of the panel capacitor.
Also, since the circuit proposed by Ooba has a voltage rising period of an X (or Y) electrode of the panel capacitor that is matched with a voltage falling period of the Y (or X) electrode, it cannot be applied to a PDP that requires different rising and falling periods.
In accordance with the present invention a power recovery PDP is provided. In one aspect of the present invention, a device for driving a PDP is provided, the PDP having a plurality of scan electrodes and sustain electrodes alternately arranged in pairs, wherein a panel capacitor is formed between the scan electrode and the sustain electrode. A first sustain and discharge unit is coupled to a first electrode of the panel capacitor, and coupled between a first power source for supplying a first voltage and a second power source for supplying a second voltage, for operating so that the first electrode may be maintained to be one of the first and the second voltages. A second sustain and discharge unit is coupled to a second electrode of the panel capacitor, and coupled between the first power source and the second power source so that the second electrode may be maintained to be one of the first and the second voltages. A charge and discharge unit, including at least one inductor coupled to the panel capacitor, is provided for converting a voltage at the second electrode into the second voltage to store energy in the inductor, using the energy stored in the inductor to convert the voltage at the first electrode into the first voltage, converting the voltage at the first electrode into the second voltage to store energy in the inductor, and using the energy stored in the inductor to convert the voltage at the second electrode into the first voltage.
The charge and discharge unit converts the voltages at the second and the first electrodes into the second and the first voltages, maintains the voltages at the first and the second electrodes to be the first and the second voltages, respectively, converts the voltages at the first and the second electrodes into the second and the first voltages, and maintains the voltages at the first and the second electrodes to be the second and the first voltages, respectively.
In another aspect of the present invention, a method for driving a PDP is provided, the PDP having a panel capacitor formed between a plurality of scan electrodes and a plurality of sustain electrodes alternately arranged with the scan electrodes, at least one inductor coupled to the panel capacitor, and a driver coupled between a first power source for supplying a first voltage and a second power source for supplying a second voltage. (a) The panel capacitor""s voltages are maintained at a first electrode and a second electrode to be the second voltage and the first voltage, respectively. (b) The voltage at the second electrode is converted into the second voltage and storing energy in the inductor. (c) The energy stored in the inductor is used to convert the voltage at the first electrode into the first voltage; (d) maintaining the voltages at the first and the second electrodes to be the first and the second voltages, respectively. (e) The voltage at the first electrode is converted into the second voltage and storing energy in the inductor. (f) The energy stored in the inductor is used to convert the voltage at the second electrode into the first voltage.
In still another aspect of the present invention, a method for driving a PDP is provided, the PDP having a panel capacitor formed between a plurality of first and second electrodes alternately arranged in pairs, a first switch and a second switch coupled in series between a first power source for supplying a first voltage and a second power source for supplying a second voltage, wherein a point where the first and the second switches meet is coupled to the first electrode of the panel capacitor, a third switch and a fourth switch coupled in series between the first power source and the second power source, wherein a point where the third and the fourth switches meet is coupled to the second electrode of the panel capacitor, at least one inductor having one end coupled to the point where the first and the second switches meet, and a fifth switch and a sixth switch respectively coupled to the inductor, wherein a point where the fifth and sixth switches meet is coupled to the point where the third and fourth switches meet. (a) The second and the third switches are turned on to maintain voltages at the first and the second electrodes to be the second and the first voltages. (b) The third switch is turned off and the sixth switch is turned on to convert the voltage at the second electrode into the second voltage. (c) The second switch is turned off and the fourth switch is turned on to convert the voltage at the first electrode into the first voltage and maintain the voltage at the second electrode to be the second voltage. (d) The sixth switch is turned off and the first switch is turned on to maintain the voltages at the first and the second electrodes to be the first and the second voltages. (e) The first switch is turned off and the fifth switch is turned on to convert the voltage at the first electrode into the second voltage. (f) The fourth switch is turned off and the second switch is turned on to convert the voltage at the second electrode into the first voltage.